This invention relates to catheters having steerable tips and particularly to a catheter having a tip which is steerable in multiple directions.
Steerable or deflectable tip cardiovascular catheters are useful in many applications, being a marked improvement over catheters with fixed tip curves. They are especially useful in the field of electrophysiology for performing radio frequency ablation of abnormal electrical pathways in the heart.
There are presently several useful designs of steerable tip catheters. One such steerable tip catheter is described in Reissue Pat. No. 34,502. The catheter has an elongated catheter body and tip portion which can be deflected into a semi-circle in one direction. In addition, the catheter body and tip portion can be rotated. Therefore by tip deflection, catheter rotation and catheter translation, i.e., lengthwise movement of the catheter, contact of the tip portion with most areas of a heart chamber may be made.
There are, however, structures and irregularity in the heart chambers which often make access difficult. In some cases it is necessary to reach around obstacles to contact a desired site. Moreover, it may be necessary to use a longer or shorter deflectable tip portion to reach a particular site and maintain adequate stable contact.
One early multidirectional deflectable tip catheter had a catheter body and tip with 5 lumens, i.e., a central lumen and four outer lumens disposed symmetrically around the central lumen. This catheter had four puller wires which extended through the outer lumens. The distal ends of the puller wires were attached to a ring at the tip and the proximal ends were attached to a xe2x80x9cjoy stickxe2x80x9d. The central lumen was open at its distal end and connected to a luer hub at its proximal end. This catheter had no reinforcement in its body or tip. It was not suitable for electrophysiology because it had effectively no torque transmission to the tip which made tip rotation difficult. Moreover, the catheter body was subject to the same deflection as the tip, but to a lesser degree.
A more recent steerable catheter has a steerable tip that is controlled by a bendable control handle. Multiple puller wires connect the steerable tip to this control handle which can be bent in any direction and can be thought of as a multiple ball joint with friction. The tip, once deflected, can be further deflected laterally by an internal stylette. The disadvantage of this catheter design is that the tip is very soft and has poor lateral stiffness due to the presence of the stylette which cannot transmit torque effectively. Because of this, an electrode at the tip of the catheter cannot be held firmly against the myocardial wall.
Another recent steerable tip catheter comprises a deflectable tip which can be deflected in one direction by a puller wire and further deflected laterally by an internal stylette. The stylette can also be moved axially within the catheter to change the shape of the tip curvature. The disadvantage of this catheter design is that the lateral stiffness of the tip is dependent upon the stylette which cannot transmit torque effectively.
In a design wherein the tip is rotated by means of a stylette, it follows that the lateral stiffness of the tip must be less than that of the stylette alone. This is because some torque from the stylette is required to rotate the tip. Moreover, the stylet must be kept small to allow the catheter body and tip to bend and to be safe within the patient body and heart.
The present invention provides a cardiovascular catheter comprising a steerable catheter tip section, an elongated catheter body and a control handle. The catheter tip section comprises at least two and preferably four off-axis lumens. The catheter body comprises at least one lumen in communication with the off-axis lumens of the catheter tip section. Preferably, the catheter body comprises a single lumen in communication with four off-axis lumens in the catheter tip section. In an alternately preferred embodiment, the catheter body comprise separate off-axis lumen aligned with each off-axis lumen of the catheter tip section. The control handle which is attached to the proximal end of the catheter body, comprises a separate movable, preferably slidable, member associated with each of the off-axis lumens of the catheter tip section.
An elongated puller wire is connected at its proximal end to each of the movable members of the control handle. Each puller wire extends through a lumen of the catheter body into the off-axis lumen in the catheter tip section and is anchored at its distal end to the wall of the catheter tip section or to a tip electrode. Movement of a movable member in the control handle results in movement of the puller wire connected to that movable member in a proximal direction relative to the catheter body and deflection of the tip section in the direction of the moved puller wire.
Preferably, the movable members are slidable within the control handle. An elongated puller wire is attached at the proximal end to each of the slidable members in the control handle. Each puller wire extends through a lumen in the catheter body into an off axis lumen in the catheter tip section and is anchored either in the lumen wall or in a tip electrode. Proximal movement of a slidable member results in proximal movement of its puller wire relative to the catheter body and deflection of the catheter tip in that off axis direction.
Means are preferably provided for resisting compression forces on the catheter body when a puller wire is moved in a proximal direction relative to the catheter body. Preferred means comprise a compression coil which extends through the catheter body in surrounding relation to each puller wire. The proximal end of the compression coil is fixedly attached to the proximal end of the catheter body and the distal end of the compression coil is fixedly attached to the distal end of the catheter body and/or at a selected location along the length of the catheter tip section. The site of the distal attachment of the compression coil and the anchor site of the puller wire associated with that compression coil in the tip section determine the length of the tip deflection curvature in the direction of that puller wire.
In a preferred embodiment of the invention, the catheter body and tip section contain four lumens arranged symmetrically in quadrants through which four puller wires extend. Each puller wire extends through a separate lumen from the control handle through the catheter body to an anchor site in the tip section. Within the catheter body, each lumen contains a compression coil in surrounding relation to the puller wire for resisting the compressive force of the puller wire, thereby preventing deflection of the catheter body. The compression coil is fixedly attached to the proximal end of the catheter body and also near the transition of the catheter body to the tip section.
In a particularly preferred embodiment of the invention, the puller wires are separated into first and second pairs, each pair containing diametrically opposed puller wires. The anchor sites of the first pair of puller wires in the tip section are more proximal to the distal end of the tip section than the anchor sites of the second pair. In this arrangement, proximal movement of a puller wire from the first pair results in a first curve of the proximal portion of the catheter tip in the direction of the quadrant of that puller wire generally in a plane containing the axis of the catheter body. Thereafter, proximal movement of an adjacent puller wire of the second pair results in a second, more distal curve in the direction of that adjacent puller wire quadrant in a plane generally transverse to the axis of the catheter body. Such a compound curve is particularly useful in reaching around obstructions such as a papillary muscle or chorda within the heart.
In a preferred embodiment of the invention, there is provided a fifth lumen located central to the four quadrant lumens. The fifth lumen runs the full length of the catheter body and tip section, or the full length of the tip section alone in a preferred embodiment. In an electrophysiology catheter, the fifth lumen may serve to carry the electrode lead wires. In other instances the fifth lumen may be open at its distal end to conduct fluids into or out of the vascular system. It may also serve to conduct other energy delivery devices such as an optical fiber, to carry a fiber optic bundle for direct viewing, to inflate a balloon, to serve as a conduit for needles and the like or other useful interventions.
In another preferred embodiment of the invention, the catheter body has a single central lumen into which the four puller wires and the lead wires from the five lumen tip converge and travel the full length of the body into the control handle. In this embodiment, the compression coils may be retained or omitted. Preferably, however, compression coils are included and the proximal ends of each of two diametrically opposed pairs of compression coils are fixedly attached to the proximal end of the catheter body. The distal ends of the compression coils are fixedly attached to the distal end of the catheter body and/or at a selected location along the length of the catheter tip section. In a preferred embodiment where one diametrically opposed pair of compression coils extends into the catheter tip and the other pair is fixedly attached to the distal end of the catheter body, it is preferable that the pair of compression coils extending into the tip is fixedly attached at a location on the tip section where the distal end of the puller wires of the other opposed pair of compression coils are fixedly attached.
Longitudinal movement of the puller wires is accomplished by means of the control handle. A preferred control handle comprises a handle body having four movable, or slidable, members. Each slidable member is connected to a puller wire so that movement, preferably proximal movement, of a slidable member from a first position towards a second position results in proximal movement of the puller wire associated with that member with respect to the catheter body and deflection of the tip section in the direction of that puller wire quadrant. Preferably, means are provided to prevent simultaneous proximal movement of diametrically opposed buttons.
These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
FIG. 1 is side view showing a preferred omni-directional catheter constructed in accordance with the present invention.
FIG. 2 is a transverse cross-sectional view of one embodiment of a catheter body showing the lumen arrangement.
FIG. 3 is a longitudinal cross-sectional view showing a preferred means for joining a catheter tip section to the catheter body.
FIG. 4 is a longitudinal cross-sectional view of the catheter tip section showing a preferred means for anchoring the puller wires.
FIG. 5a is a longitudinal cross-sectional view of a preferred puller wire T-bar anchor.
FIG. 5b is a longitudinal cross-sectional view of a preferred puller wire T-bar anchor of FIG. 5a rotated 90xc2x0 C. to show the cross-piece on end.
FIGS. 6a and 6b are longitudinal cross-sectional views of the catheter tip section showing other preferred means for anchoring the puller wires.
FIG. 7 is a perspective view of a tip section deflected into a compound curve.
FIG. 8 in a longitudinal cross-sectional view of a preferred control handle.
FIG. 9 is a transverse cross-sectional view of the control handle of FIG. 8 taken along line 9xe2x80x949 without insert 79.
FIG. 10 is a transverse cross-sectional view of a preferred means for securing the puller wire to the control handle.
FIG. 11 is a transverse cross-sectional view of a presently preferred catheter body construction.
FIG. 12 is a longitudinal cross-sectional view of the proximal end of the catheter body of FIG. 11.
FIG. 13 is longitudinal cross-sectional view of a preferred means of joining a catheter body to the deflectable catheter tip and of attaching compression coils to the deflectable tip.
FIG. 14 is a transverse cross-sectional view of the tip section of FIG. 13 taken along line 14xe2x80x9414.